Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/12—Chemical modification
  • C08J7/16—Chemical modification with polymerisable compounds
  • C08J7/18—Chemical modification with polymerisable compounds using wave energy or particle radiation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/36—After-treatment
  • C08J9/40—Impregnation
  • C08J9/405—Impregnation with polymerisable compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2201/00—Foams characterised by the foaming process
  • C08J2201/02—Foams characterised by the foaming process characterised by mechanical pre- or post-treatments
  • C08J2201/03—Extrusion of the foamable blend
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2201/00—Foams characterised by the foaming process
  • C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
  • C08J2201/052—Inducing phase separation by thermal treatment, e.g. cooling a solution
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2201/00—Foams characterised by the foaming process
  • C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
  • C08J2201/054—Precipitating the polymer by adding a non-solvent or a different solvent
  • C08J2201/0542—Precipitating the polymer by adding a non-solvent or a different solvent from an organic solvent-based polymer composition
  • C08J2201/0543—Precipitating the polymer by adding a non-solvent or a different solvent from an organic solvent-based polymer composition the non-solvent being organic
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2201/00—Foams characterised by the foaming process
  • C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
  • C08J2201/054—Precipitating the polymer by adding a non-solvent or a different solvent
  • C08J2201/0545—Precipitating the polymer by adding a non-solvent or a different solvent from an aqueous solvent-based polymer composition
  • C08J2201/0546—Precipitating the polymer by adding a non-solvent or a different solvent from an aqueous solvent-based polymer composition the non-solvent being organic
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2323/10—Homopolymers or copolymers of propene
  • C08J2323/12—Polypropene

Definitions

• This invention relates to a hydrophilic porous material sterilizable with ⁇ -ray. More particularly, it relates to a ⁇ -ray-sterilizable hydrophilic porous material which is used favorably in the medical field as for purification of blood and separation of blood plasma, for example.
• porous materials made of hydrophobic polymer substances represented by such polypropylene type porous materials as described above indeed excel in such properties as chemical resistance, dimensional stability, and mechanical strength and nevertheless require to undergo a treatment for imparting of hydrophilicity as by alcohol-water displacement before they are put to use for the treatment of aqueous media. Imparting hydrophilicity proves to be extremely complicated operationally.
• porous materials made of hydrophobic polymer substances as by coating their surfaces with such hydrophilic materials as surfactant, polyethylene glycol, and polyvinyl alcohol cross-linking and insolubilizing them with polymers formed mainly of such hydrophilic monomers as N,N-dimethyl acrylamide, 2-­hydroxyethyl methacrylate, and N-vinyl pyrrolidone.
• hydrophilic materials as surfactant, polyethylene glycol, and polyvinyl alcohol cross-linking and insolubilizing them with polymers formed mainly of such hydrophilic monomers as N,N-dimethyl acrylamide, 2-­hydroxyethyl methacrylate, and N-vinyl pyrrolidone.
• the porous materials which have hydrophilicity imparted thereto by these methods are invariably found to induce exudation in consequence of exposure to ⁇ -ray.
• Use of these porous materials in medical materials therefore, has a problem of dubious safety.
• An object of this invention is to provide a novel hydrophilic porous material sterilizable with ⁇ -ray.
• Another object of this invention is to provide a ⁇ -­ray-sterilizable hydrophilic porous material which is used favorably in the medical field as for purification of blood and separation of blood plasma.
• the further object of this invention is to provide a ⁇ -­ray-sterilizable hydrophilic porous material which retains practical bursting elongation even after exposure to ⁇ -ray, yields to exudation only sparingly, and ensures high safety.
• a ⁇ -­ray-sterilizable hydrophilic porous material which comprises supported on at least part of its surface, a continuous layer made of a synthetic polymer compound forming a porous substrate not less than 5% by weight, based on the substrate, of a hydrophilic and ⁇ -ray-resistant polymer and possessing an average pore diameter in the range of 0.02 to 20 km, a porosity in the range of 10 to 90%, and a wall thickness in the range of 10 km to 5.0 mm.
• This invention further discloses a ⁇ -ray-­sterilizable hydrophilic porous material, wherein the hydrophilic and ⁇ -ray-resistant polymer is formed mainly of an alkoxyalkyl (meth)acrylate.
• This invention further discloses a ⁇ -ray-sterilizable hydrophilic porous material, wherein the hydrophilic and ⁇ -ray-resistant polymer is formed mainly of a monomer represented by the following general formula I: wherein R1 is an alkylene group or a polymethylene group each of 1 to 4 carbon atoms, R2 is an alkyl group of 1 or 2 carbon atoms or an alkoxyalkyl group of 2 to in carbon atoms, and R3 is hydrogen atom or methyl group.
• This invention further discloses a ⁇ -ray-sterilizable hydrophilic porous material, wherein the synthetic polymer compound forming the porous substrate is formed mainly of a polyolefin or a halogenated polyolefin and the bursting elongation after exposure to ⁇ -ray is not less than 5%.
• This invention further discloses a ⁇ -ray-sterilizable hydrophilic porous material, wherein the synthetic polymer compound forming the porous substrate is formed mainly of a polyolef in or a polyvinylidene fluoride and the difference between the maximum absorption wavelengths of 350 and 220 nm of the autoclave extract after exposure to ⁇ -ray is not more than 0.1, based on that of the blank.
• the porous material of this invention is characterized by having supported on at least part of the surface of a continuous layer made of a synthetic polymer compound forming a porous substrate not less than 5% by weight, based on the substrate, of a hydrophilic and ⁇ -­ray-resistant polymer and possessing an average pore diameter in the range of 0.02 to 20 km, a porosity in the range of 10 to 90%, and a wall thickness in the range of 10 ⁇ m to 5.0 mm. It possesses sufficient hydrophilicity and exhibits high mechanical strength safety as regards exudation. It, therefore, can be expected to find favorable utility in the medical field as for purification of blood and separation of blood plasma. Since, it allows effective application of a method of sterilization with ⁇ -ray, it can be sterilized infallibly and rapidly.
• the porous material of the present invention acquire further prominent hydrophilicity and ⁇ -ray resistance when the hydrophilic and ⁇ -ray-resistant polymer is formed mainly of an alkoxyalkyl (meth)acrylate or when it is formed mainly of a monomer represented by the general formula I. Further the porous material excels in such physical properties as mechanical strength and chemical resistance when the synthetic polymer compound forming the porous substrate is formed mainly of a polyolefin, a halogenated polyolefin, or a polyvinylidene fluoride. Thus, the material is highly suitable for medical materials.
• the ⁇ -ray-sterilizable hydrophilic porous material of the present invention is characterized by having supported on at least part of its surface a continuous layer made of a synthetic polymer compound forming a porous substrate not less than 5% by weight, based on the substrate, of a hydrophilic and ⁇ -ray-­resistant polymer and possessing an average pore diameter in the range of 0.02 to 20 ⁇ m, a porosity in the range of 10 to 90%, and a wall thickness in the range of 10 ⁇ m to 5.0 mm.
• the porous material of the present invention is constructed as described above and, therefore, possesses outstanding hydrophilicity.
• the expression "possessing hydrophilicity” as used in the present specification refers to the possession by a porous material of at least such a characteristic that when water is allowed to fall gently in drops on the porous material at room temperature (200 ⁇ 5°C), it penetrates the pores in the porous material by virtue of its own weight and permeates to the further side of the porous material within 5 minutes.
• the porous material of this invention excels in resistance to ⁇ -ray and precludes the problem of deterioration of mechanical strength and occurrence of exudation after exposure to the ⁇ -ray.
• it is preferable to possess a bursting elongation of not less than 5% after exposure to ⁇ -ray and a difference of not more than 0.1, based on that of the blank, between the maximum absorption wavelength of 350 and 220 nm of the autoclave extraction after exposure to ⁇ -ray.
• exposure to ⁇ -ray means the fact that a given porous material is exposed to ⁇ -­ray in a dose of 2 Mrads, the magnitude enough for sterilization of the porous material.
• bursting strength represents the magnitude determined with a tensile tester, using a sample 10 mm in width with the chuck distance set at 60 mm.
• exudation represents the quality determined of an extract obtained by placing 1.0 g of a given porous material in 100 ml of high-­purity deionized water (based on artificial kidney) and treating the immersed sample in an autoclave at 115°C for 30 minutes. This magnitude contemplated by the present invention, therefore, may well be regarded as a highly safe criterion because the sample would have produced a smaller extract under the conditions employed popularly.
• the shape to be given to the hydrophilic porous material of this invention is not specifically defined but may be a hollow fiber, a flat membrane, or a ring, for example.
• the wall thickness of the porous material is defined by the range of 10 ⁇ m to 5.0 mm. The reason for this range is that the porous material allows no easy handling in terms of strength when the thickness is less than 10 ⁇ m and that the treatment for surface improvement with a hydrophilic and ⁇ -ray-resistant polymer to be performed as described hereinafter possibly proceeds ununiformly in the direction of wall thickness and modules incorporating the hydrophilic porous material gain intolerably in volume when the wall thickness exceeds 5.0 mm.
• the average pore diameter is defined by the range of 0.02 to 20 ⁇ m.
• the reason for this range is that the treatment to be given to the interior of membrane is attained only with difficulty when the average pore diameter is less than 0.02 ⁇ m and that the porous material allowed no easy handling on account of deficiency in strength.
• the porosity is defined by the range of 10 to 90%. The reason for this range is that the porous material acquires no sufficient perviousness to air or liquid and retards the clinical treatment with the porous material when the porosity is less than 10% and that the porous material possibly suffers from deficiency in practically tolerable strength because the continuous phase is extremely deficient in thickness and volume.
• the porous substrate is not particularly discriminated on account of the synthetic polymer compound to be selected as the material therefor.
• synthetic polymer compounds are available for the formation of the porous substrate. They are, however, preferable to possess highly satisfactory physical and chemical characteristics.
• synthetic polymer compounds include polyolefins such as polyethylene and polypropylene, partially chlorinated or fluorinated polyolefins such as ethylene-dichlorodifluoroethylene copolymers, polyamides such as nylon 6 and nylon 6,6, saturated polyesters such as polyethylene terephthalate, polyacrylonitrile, and polyvinylidene fluoride, for example.
• polyolefins, halogenated polyolefins, and polyvinylidene fluoride prove to be particularly desirable.
• the hydrophilic and ⁇ -ray-resistant polymer to be retained on at least part of the surface of the continuous phase of the porous membrane forming the substrate is preferable to be formed mainly of an alkoxyalkyl (meth)acrylate.
• alkoxyalkyl (meth)acrylates which are available, those represented by the following general formula I: wherein R1 is an alkylene of 1 to 4 carbon atoms such as CH2, C2H4, C3H4 or C4H8 or a polymethylene group, R2 is an alkyl group of 1 or 2 carbon atoms such as CH3 or C2H5 or an alkoxyalkyl group of 2 to in carbon atoms such as C2H4OC2H5, C2H4OCH3, CH2OC2H5, or CH2OCH3, and R3 is hydrogen atom or methyl group) may be cited as particularly preferable monomers.
• alkoxyalkyl (meth)acrylates which are usable herein specifically include methoxymethyl (meth)acrylates, methoxyethyl (meth)acrylates, methoxypropyl (meth)acrylates, methoxybutyl (meth)acrylates, ethoxymethyl (meth)acrylates, ethoxyethyl (meth)acrylates, ethoxypropyl (meth)acrylates, ethoxybutyl (meth)acrylates, (2-­ethoxyethoxy)methyl (meth)acrylates, diethylene glycol monoethyl ether (meth)acrylates, 3-(2-ethoxyethoxy)propyl (meth)acryaltes, 4-(2-ethoxyethoxy)butyl (meth)acrylates, (2-methoxyethoxy)methyl (meth)acrylates, diethylene glycol monomethyl ether (meth)acrylates, 3-(2-methoxyethoxy)propyl (meth)
• the polymerizable monomer is only required to be formed mainly of at least one monomer selected from the monomers mentioned above.
• the retention of the hydrophilic and ⁇ -ray-­resistant polymer on at least part of the surface of the continuous layer formed of a synthetic polymer compound forming the aforementioned porous substrate may be attained by physically coating the surface with the polymer, it is attained preferable by binding the polymer in the form of a graft chain to the at least part of the surface of the continuous phase of the porous substrate.
• this surface grafting is preferable to be carried out by a method which comprises exposing a porous membrane destined to form the substrate to low-temperature plasma and then allowing the porous membrane to contact a monomer supplied thereto in a gaseous form thereby inducing graft polymerization of the monomer and binding a preferable polymer chain to the porous membrane by virtue of the resultant graft polymerization [JP-A-62-262,705 (1987)].
• the hydrophilic and ⁇ -ray-resistant polymer should be retained as described above in an amount exceeding 5% by weight, preferably falling in the range of 10 to 50% by weight, based on the amount of the porous substrate. If the amount of the polymer to be retained is less than 5% by weight, there is a fair possibility that the produced porous material will acquire no fully satisfactory hydrophilicity and suffer from deficiency in physical properties. Further, if the amount is exceeding 50 % by weight, properties of the substrate sometimes decreases (for example, pores are blocked.)
• a biaxial extruding device 100 parts by weight of a mixture of two species of polypropylene having melt indexes of 30 and 0.3 (weight ratio 100 : 40), 400 parts by weight of liquid paraffin (number average molecular weight 324), and 0.3 part by weight of 1,3,2,4-bis(p-­ethylbenzylidene) sorbitol as a crystal seed forming agent were melted and kneaded and pelletized.
• the pellets were melted, extruded into the ambient air through a T-die having a slit width of 0.6 mm, led into a cooling and solidifying liquid by the rotation of guide rollers of a cooling liquid tank installed directly under the T-die, and taken up.
• a fixed length of the film was cut out, fixed at the opposite longitudinal ends thereof, immersed a total of four times each for 10 minutes in 1,1,2-trichloro-1,2,2-trifluoroethane thereby expelling the liquid paraffin by extraction therefrom, and heat-­treated in the air at 135°C for two minutes, to obtain a porous polypropylene membrane having an average pore diameter of 0.6 ⁇ m, a porosity of 69%, and a wall thickness of 130 ⁇ m.
• the porous membrane produced as described above was exposed to a low-temperature plasma (Ar, 0.1 Torr) for 10 seconds and allowed to contact a varying monomer indicated in Table 1 in the gaseous phase under the temperature condition of 14.85°C (288K) to effect surface graft polymerization.
• the graft polymerized porous membrane was washed with a solvent (methanol) for two days and dried.
• the graft-treated porous material thus obtained was tested for hydrophilicity, bursting elongation after ⁇ -ray exposure, and difference in maximum absorption wavelength at 350-220 nm of an autoclave extract after the ⁇ -ray exposure. The results are shown in Table 1.
• This property was determined by irradiating a sample porous material with ⁇ -ray at a dose of 2 Mrads stretching the sample with a tensile tester (produced by Toyo Seiki K.K. and marketed under trademark designation of "Strograph T ⁇ ), with a sample width fixed at 10 mm and a chuck distance at 60 mm.
• a tensile tester produced by Toyo Seiki K.K. and marketed under trademark designation of "Strograph T ⁇
• This test was performed by irradiating a sample porous material with ⁇ -ray at a dose of 2 Mrads, cutting a portion 1.0 g in weight from the porous material, placing the portion in 100 ml of high-purity deionized water, autoclaving the immersed portion under the conditions of 115°C and 30 minutes prescribed as standards for an artificial internal organ, measuring the maximum absorption wavelengths of the exudation at 350 to 220 nm, and finding the difference, UV, from a blank (deionized water undergone autoclaving treatment).

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Toxicology (AREA)
• General Chemical & Material Sciences (AREA)
• Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• External Artificial Organs (AREA)
• Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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• 1990
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